All about Solar PV
Solar cells, also called photovoltaic (PV) cells by scientists, convert sunlight directly into electricity. PV gets its name from the process of converting light (photons) to electricity (voltage), which is called the PV effect.
Solar cells/photovoltaics to convert sunlight directly into electricity by converting photons (light particles) into electrons (negatively charged particles). Photovoltaic cells are made of semiconductors and silicon, mixed with other material.
Solar cell efficiencies vary from 6% for amorphous silicon-based solar cells to 44.0% with multiple-junction production cells and 44.4% with multiple dies assembled into a hybrid package. Solar cell energy conversion efficiencies for commercially available multicrystalline Si solar cells are around 14-19%. The highest efficiency cells have not always been the most economical — for example a 30% efficient multijunction cell based on exotic materials such as gallium arsenide or indium selenide produced at low volume might well cost one hundred times as much as an 8% efficient amorphous silicon cell in mass production, while delivering only about four times the output.
A common method used to express economic costs is to calculate a price per delivered kilowatt-hour (kWh). The solar cell efficiency in combination with the available irradiation has a major influence on the costs, but generally speaking the overall system efficiency is important. Commercially available solar cells (as of 2006) reached system efficiencies between 5 and 19%.
Capacity factor is a measure of how much energy is produced by a plant compared with its maximum output. It is measured as a percentage, generally by dividing the total energy produced during some period of time by the amount of energy the plant would have produced if it ran at full output during that time.
The capacity factor compares the actual output of a PV array compared to the energy it would produce if it operated at full capacity all the time. With solar power, maximum capacity factor for a fixed PV array tends to be of around 27%, since the technology is unable to produce energy during the night and even during the day only partial sunlight is available in the early morning or in the evening. Capacity factors close to 100% would be unrealistic for solar power, unless it was for an array mounted on a probe in outer space where sunlight is available all the time.
BASIC FORMULA
The formula for calculating the capacity factor is:
CAPACITY FACTOR = OUTPUT OVER GIVEN TIME PERIOD (kWh) / [ HOURS OF TIME PERIOD x INSTALLED CAPACITY (kW) ]
The time period can be days, months or years. For example, a PV array with 100 kW of capacity providing 17,500 kWh / month would have a capacity factor of:
CAPACITY FACTOR = (17,500 kWh) / (24 h/day x 30 day/month x 100 kW) = 0.243 = 24.3%
ALTERNATIVE FORMULA
Since the output of a solar PV system is related directly with peak sun-hours available, it is possible to calculate the maximum theoretical capacity factor at a given location by dividing:
MAX CAPACITY FACTOR = PEAK SUN HOURS PER DAY / 24 HOURS
For instance, the most favorable locations in the world tend to have 6.5 peak sun-hours per day, in this cases the capacity factor would be:
CAPACITY FACTOR = 6.5 hours / 24 hours = 0.27 = 27%
This will be achieved if the solar PV array is positioned in such a way that maximizes the incident solar radiation.
Capacity factors may be increased beyond the theoretical limit of fixed systems with tracking technology, which provides a higher kWh output while conserving the PV system's installed capacity.
Reference: https://www.nrel.gov/pv/national-center-for-photovoltaics.html (07-17-2018)